1. Field of the Invention
The present invention relates to an electrically-driven steering lock device which is applied to a vehicle such as an automobile or the like.
2. Description of the Related Art
Vehicles such as automobiles and the like are equipped with, for example, a so-called electrically-driven steering lock device as an antitheft device. The electrically-driven steering lock device has, for example, a lock body which is assembled to the steering post of a vehicle. The lock body has a main body portion, which houses a driving means, and a guide portion, which is tubular and projects from the main body portion toward the steering shaft. The main body portion and the guide portion are integral. Within the main body portion, a cam portion is connected to a motor which is the driving means. The cam portion rotates in accordance with the forward and reverse rotation of the motor. A lock stopper and a lock bar are disposed within the tube of the guide portion. The lock stopper is movable in accordance with the rotation of the cam portion, and is urged by a spring toward the steering shaft. One end portion of the lock bar is engaged with the lock stopper.
In an electrically-driven steering lock device having the above-described structure, the distal end portion of the lock bar projects toward the steering shaft and locks the steering shaft such that rotation thereof is not possible. The lock stopper and the lock bar are moved by the cam portion in the direction opposite the steering shaft against the urging force of the spring, such that the engagement of the lock bar with the steering shaft is cancelled.
On the other hand, among usual steering lock devices which are operated by a key, there is a type which has basically the same structure as that of the above-described electrically-driven steering lock device. In this steering lock device, a key cylinder in which a key is inserted is housed in the main body portion. A cam portion of a cam shaft is rotated by the operation of rotating the key which is inserted in the key cylinder. Then, in accordance with the rotation of the cam portion, the lock stopper and the lock bar move within the tube of the guide portion.
At times such as when the vehicle suddenly decelerates or the like, the knee of the driver may strongly hit the main body portion or the guide portion of the lock body, and receive a great impact. Therefore, the applicant of the present application has proposed a steering lock device in which, when the main body portion or the guide portion of the lock body receives an impact force of a predetermined value or more, the intermediate portion of the guide portion breaks, and the impact which the driver receives is thereby lessened (see Japanese Patent Application Laid-Open (JP-A) No. 7-9944).
Moreover, the steering lock device disclosed in JP-A No. 7-9944, is provided with an impeding means such that, accompanying the breaking of the guide portion of the lock body, the engagement of the lock stopper and the lock bar is cancelled, the lock bar becomes able to move, and locking of the steering shaft of the vehicle which is in the midst of traveling is impeded. Namely, an engaging member, which is urged toward the lock bar and whose movement is restricted at usual times, is provided at the distal end side of the guide portion. Accompanying the breaking of the intermediate portion of the guide portion, this restriction is cancelled, and the engaging member is moved and made to engage with an engaging portion provided at the lock bar. Movement of the lock bar is thereby restricted.
In accordance with this structure, in cases in which the lock body is broken due to an illegal act when the vehicle is parked, movement of the lock bar can be restricted by the engaging member, and it is possible to maintain the state in which the steering shaft is locked by the lock bar (a so-called “dead locking mechanism”).
However, in the above-described steering lock device disclosed in JP-A No. 7-9944, the engaging member and the restricting member which restricts movement of the engaging member are exposed at the exterior of the lock body. Therefore, there is the concern that the engagement of the engaging member with the lock bar can be impeded by fixing the engaging member in advance before breaking the lock body.
Thus, the applicant of the present application has proposed a steering lock device whose antitheft quality is improved by providing such an engaging member and restricting member at the interior of the lock body (refer to JP-A No. 2000-225922).
In this steering lock device disclosed in JP-A No. 2000-225922, a cam shaft is provided within the guide portion. When the lock body is broken, the main body portion and the guide portion are divided. Movement of the engaging member is restricted by a restricting member which is disposed between the guide portion and the cam shaft and whose one end is fixed to the main body portion. Therefore, accompanying the division of the main body portion and the guide portion, the restricting member is eliminated. Therefore, the engaging member moves toward the cam shaft and engages with an engaging hole provided in the cam shaft. Movement of the cam shaft, the lock stopper, and the lock bar is thereby restricted.
However, in the above-described steering lock device disclosed in JP-A No. 2000-225922, because the restricting member is cleared away together with the main body portion as the main body portion and the guide portion are divided, a gap forms between the guide portion and the cam shaft. Therefore, there is the possibility that the position of the engaging member will be specified from this gap, and that the engaging member which is engaged with the cam shaft may be removed in some way. Thus, there is the need for a countermeasure to prevent such a situation from occurring.